Angle-resolved photoemission observation of isotropic superconducting gaps in isovalent Ru-substituted Ba(Fe${}_{0.75}$Ru${}_{0.25}$)${}_{2}$As${}_{2}$

Angle-resolved photoemission observation of isotropic superconducting gaps in isovalent Ru-substituted Ba(Fe $_{0.75}$ Ru $_{0.25}$ ) $_{2}$ As $_{2}$

N. Xu, P. Richard, X.-P. Wang, X. Shi, A. van Roekeghem, T. Qian, E. Ieki, K. Nakayama, T. Sato, E. Rienks, S. Thirupathaiah, J. Xing, H.-H. Wen, M. Shi, T. Takahashi, and H. Ding

Phys. Rev. B 87, 094513 – Published 18 March 2013

Abstract

We used high-energy resolution angle-resolved photoemission spectroscopy to extract the momentum dependence of the superconducting gap of Ru-substituted Ba(Fe $_{0.75}$ Ru $_{0.25}$ ) $_{2}$ As $_{2}$ ( $T_{c} = 15$ K). Despite a strong out-of-plane warping of the Fermi surface, the magnitude of the superconducting gap observed experimentally is nearly isotropic and independent of the out-of-plane momentum. More precisely, we respectively observed 5.7 and 4.5 meV superconducting gaps on the inner and outer $Γ$ -centered hole Fermi surface pockets, whereas a 4.8 meV gap is recorded on the $M$ -centered electron Fermi surface pockets. Our results are consistent with the $J_{1} - J_{2}$ model with a dominant antiferromagnetic exchange interaction between the next-nearest Fe neighbors.

Received 17 December 2012

DOI:https://doi.org/10.1103/PhysRevB.87.094513

Authors & Affiliations

N. Xu¹, P. Richard^1,*, X.-P. Wang¹, X. Shi¹, A. van Roekeghem^1,2, T. Qian¹, E. Ieki³, K. Nakayama³, T. Sato^3,4, E. Rienks⁵, S. Thirupathaiah⁶, J. Xing⁷, H.-H. Wen⁷, M. Shi⁸, T. Takahashi^3,9, and H. Ding^1,†

¹Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
²Centre de Physique Théorique, Ecole Polytechnique, CNRS-UMR7644, 91128 Palaiseau, France
³Department of Physics, Tohoku University, Sendai 980-8578, Japan
⁴TRiP, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
⁵Helmholtz-Zentrum Berlin, BESSY, D-12489 Berlin, Germany
⁶Institute for Solid State Research, IFW Dresden, D-01171 Dresden, Germany
⁷Center for Superconducting Physics and Materials, National Laboratory for Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, China
⁸Paul Scherrer Institut, Swiss Light Source, CH-5232 Villigen PSI, Switzerland
⁹WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

^*p.richard@iphy.ac.cn
^†dingh@iphy.ac.cn

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Vol. 87, Iss. 9 — 1 March 2013

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